Known wind turbines used for wind turbine generator include wind turbines in which the pitch angle of wind-turbine rotary blades is fixed and wind turbines in which the pitch angle is variable.
As a mechanism for changing the pitch angle of the wind-turbine rotary blades, as mentioned above, for example, a mechanism for converting linear movement of a rod of a hydraulic cylinder to rotation around the axis of the wind-turbine rotary blades is known (for example, refer to Patent Document 1).
In addition to the mechanism described in the above-mentioned Patent Document 1, there is a known variable-pitch structure in which a hydraulic cylinder is supported by a trunnion structure at a rotor head in a such a manner that the hydraulic cylinder rotates around a single axis and in which an end of a rod is supported in such a manner that it rotates around a single axis of a wind-turbine rotary blade.
In this variable-pitch structure, the hydraulic cylinder and the rod are supported in a plane perpendicular to the axis of the wind-turbine rotary blades in such a manner that they are turnable around the trunnion structure, i.e., pivot around a single axis. Since the end of the rod is supported at a position away from the axis of the wind-turbine rotary blades, the linear movement of the rod was converted to rotation around the axis of the wind-turbine rotary blades.
Patent Document 1:
Japanese Unexamined Patent Application, Publication No. HEI-5-149237